The purpose of the organ culture and tissue processing core facility (core B) is to provide a centralized source of metanephroi for biochemical, tissue culture, in situ hybridization, and immunohistochemical analysis by the five participating laboratories. Obtaining and maintaining metanephroi entail considerable skill and experience already possessed by the personnel of the facility. This core will free the time and resources that the project directors would have had to otherwise devote to tissue preparation and facilitate their progression along the proposed lines of investigation. The facility will assure uniformity, allowing cross comparisons of the timing of observed changes in transport proteins, growth related genes and factors, and structure. The core will minimize duplication of equipment and decrease expenditures. The centralization of maintaining metanephric organ culture and tissue processing will assure uniformity and reproducibility of observations made in separate laboratories.